The present disclosure generally relates to a surgical distance adjusting assembly for use in surgical procedures. In particular, a surgical distance adjusting assembly for a bone distractor, the bone distractor as well as a system comprising the bone distractor are described.
When performing a reconstructive osteotomy or segment advancement of a cranium or jaw bone, the bone is typically separated into two or more sections. Plates of a bone distractor are then fixed to the respective bone sections by bone screws.
After their fixation to bone, the plates are successively distracted. The bone distractor may be operated by rotating a wire through an incision in the skin of the patient. The successive separation of the bone sections causes new bone to form in the generated gap, whereby the bone is gradually lengthened. During the formation of new bone in the gap, the distractor maintains a fixed gap width.
U.S. Pat. No. 6,908,469 discloses a maxillary bone distractor comprising a lead screw having an external thread in engagement with an internal thread of an inner sleeve. The distal end of the inner sleeve is fixed to a distal plate. The lead screw is journaled within an outer sleeve having an external thread to which a proximal plate is coupled. The outer sleeve is rotationally fixed relative to the inner sleeve.
After the distraction operation and a consolidation phase, the entire bone distractor (including the plates) has to be explanted, since the plates are fixed to the bone distractor. Thus, two significant invasive surgical procedures, namely one to implant the bone distractor device and another to remove it after the consolidation phase of bone, are necessary.
U.S. Pat. No. 6,423,069 discloses an orthopedic system comprising two plates each having a faster-connecting portion. The proximal plate is coupled to a proximal fastener by a detent mechanism, wherein a depression is provided on the proximal plate and an arm with a projection complementary to the shape of the depression is provided on the proximal fastener. When an outer sleeve is threaded into a bore of the proximal fastener, the arm projects out of the fastener into the depression of the proximal plate. Thus, the arm holds the proximal plate in position and prevents disengagement of the detent mechanism even when subjected to substantial forces such as those generated during the removal of the orthopedic device. The distal plate has a fastener-connecting portion generating a slip lock between a distal fastener and the distal plate. An inner sleeve is connected with its distal end to a bore of the distal fastener.
After the distraction operation and a consolidation phase, the device is removed by rotating the bone distractor to cause the distal fastener to disengage from the distal plate. Then, the outer sleeve has to be unthreaded from the proximal fastener to allow the arm to flex, such that when the device is pushed towards the bone surface, the detent mechanism holding the proximal fastener to the corresponding proximal footplate is released.
Although the orthopedic system of U.S. Pat. No. 6,423,069 is intended to provide a device that does not require a second surgical procedure to remove the device after the orthopedic procedure is completed, the system of U.S. Pat. No. 6,423,069 has several drawbacks. The orthopedic system has a bulky and very complicated structure which does not efficiently utilize its size. Further, due to the complicated removal mechanism, several steps are necessary to remove the bone distractor, wherein the sleeves, the fasteners and the plates may get stuck or jammed during explantation. The large size of the distractor and the complicated bone plate holding and removal mechanism also lead to more interference with surrounding tissue, with an increased risk of infections.
U.S. Pat. No. 5,895,387 discloses a distractor for craniofacial bone distraction. The bone distractor has first and second clamps are slideably connected via rods. The rods are connected to the first clamp and extend through holes in the second clamp. The second clamp includes a threaded hole through which extends a threaded rod. The threaded rod has an end engaging an anvil area of the first clamp. Further, each clamp includes holes for receiving bone pins or bone screws to directly attach the clamps to bone. As threaded rod is turned, an expansion force is generated between the first and second clamp. Thus, similar to the distractor of U.S. Pat. No. 6,908,469, two invasive surgical procedures, namely one to implant the bone distractor and another to remove it after the consolidation phase of bone, are necessary.
U.S. Pat. No. 7,771,434 B2 discloses a bone distractor having a threaded rod rotatably disposed within an elongated tubular housing. The elongated housing is provided with an axial slot, wherein a proximal plate-mounting means is in communication with the threaded rod such that rotation of the threaded rod results in movement of the proximal plate-mounting means in the proximal axial direction. Further, a distal plate-mounting means is affixed to the distal end of the housing. The distal and proximal plate-mounting means comprise U-shaped brackets for receiving bone plates. The bone plates are secured to the brackets and to the bone segments by bone screws inserted through apertures in the brackets and in the bone plates.